Scaffold



Dec. 25, 1956 Filed May 20, 1955 E. W. HAGADORN SCAFFOLD 3 Sheets-Sheetl INVENTOR. ELMoRe \rJ. HAGADORN BY R11! \IEr-Km ATTORNEY.

Dec. 25, 1956 E. w. HAGADORN 2,775,489

SCAFFOLD Filed May 20, 1955 5 Sheets-Sheet 2 INVENTOR. ELMORE W.Has-anon BY I ucmK am.

A TTURN EY. I

Dec. 25, 1956 E. w. HAGADORN 2,775,489

5 Sheets-Sheet 3 Filed May 20, 1955 INVENTOR. ELMDRE W. Haemacmn (31AM!mam.

ATTORNEY.

United States Patent SCAFFOLD Elmore W. Hagadorn, Solvay, N. Y.,assignor to Finishine Laboratories, Inc., Syracuse, N. Y., a corporationof New York Application May 20, 1955, Serial No. 509,891

Claims. (Cl. 304-28) This invention relates generally to scaffoldconstructions, and has particular reference to a novel scaffold ortemporary support for workmen engaged in tree surgery, telephone orpower line work, steeple repair work, and the like.

At the present time, it is usually the practice for workmen operating inelevated positions on trees, telephone poles and the like to supportthemselves by means of boot spurs and waist harnesses. The boot spurs orirons are thrust into the tree or poleand bear most of the workmansweight while the waist harness or strap is fastened around the pole andholds the workman in a substantially upright position so that his armsand hands are free to perform his taskl This arrangement leaves much tobe desired since the spur support places a great strain on the workmanslegs, and the waist strap exerts an uncomfortable pressure on the kidneyarea of his back. As a result, the average workman can not remain at hisstation for extended periods of time but must descend to the ground atfrequent intervals to rest and relax his muscles.

Since it is necessary for the workman equipped with boot spurs and awaist harness to frequently interrupt his work for rest periods, it willbe apparent that the time necessary to'complete the work and the cost ofthe labor are both greater than they would be if the work could beperformed continuously. This inefficiency has led to various attempts inthe past to provide an improved support means for this type of work, andseveral devices having a seat type support for the workman have beendeveloped. Most of these devices, however, have proved to be of limitedutility or have not had sufficient stability to enable the Workman touse them with any confidence or comfort. At the other extreme, a specialtruck has been developed which is equipped with a hydraulically operatedplatform that can lift a workman to an elevated position adjacent apower line or the like and support him in safety and comfort while heperforms his work. This equipment, however, represents a relativelylarge capital investment and at the present time is used chiefly only bylarge telephone and power companies since it is beyond the means of mostsmall companies and independent operators.

With the foregoing and other considerations in view, it is the primaryobject of the present invention therefore to provide a greatly improvedscaffold for workmen engaged in tree surgery, telephone or power linework, and the like, which scaffold provides a very safe and comfortablesupport for the workmen and yet can be manufactured at a moderate cost.

Another very important object of the present invention is to provide ascaffold for. tree surgeons, telephone or power linemen, and the like,which enables a workman to sit or stand comfortably while performing hiswork, without any undue strain on his legs or back, so the workcan beperformed continuously. without the necessity for frequent rest periods.M

A further important object of the invention is to pro- 2,775,489Patented Dec. 25, 1956 vide a scaffold for tree surgeons, linemen, andthe like, which can be attached to a tree, pole or other upright supportin such a manner that it is extremely stable and can safely support theweight of several workmen.

Still another important object of the invention is to provide a scaffoldfor tree surgeons, linemen, and the like, which is easily portable andcan be carried and operated by one man.

A still further important object of the invention is to provide ascaffold for tree. surgeons, linesmen, and the like, which is strong anddurable and has utility in a large number of applications.

A more specific object of the inventionis to provide a scaffold for thepurposes described which is readily collapsible' so that it is easy totransfort and will fit into a relatively small space when not in use.

A further specific object of the invention is to provide a scaffold forthe purposes described which can be hoisted up on a tree, pole or otherfixed support while the workman is on the scaffold.

Another specific'object' of the invention is to provide a scaffold forthe purposes described which can be attached to a tree, pole or otherfixed support at any height and at substantially 'anyangle, the scaffoldbeing adapted for attachment to supports having a wide range of crosssectional areas.

Still -another specific object of the invention is to provide a scaffoldfor the purposes described having an interchangeable saddle seat andplatform arrangement, the platform being adapted to support up to threeworkmen in a standing position.

Other objects and advantages of the invention will become apparent fromthe following detailed description thereof read in conjunction with theaccompanying draw ings which illustrate a preferred embodiment of theinvention for the purpose of disclosure.

In the drawings:

Figure l is a top plan view of an improved scaffold embodying theinvention;

Figure 2 is a side elevation of the scaffold shown in Figure l; i

Figure 3 is a vertical section taken along line 3-3 of Figure 1, showingone position of the movable spikes and earn actuator therefor;

Figure 4 is a section corresponding to the section of Figure 3, showing.another position of the movable spikes and cam actuator;

Figure 5 is a horizontal section taken along line 55 of Figure 3;

Figure 6 is a horizontal section taken line 66 of Figure 2;

Figure 7 is a fragmentary side elevation showing an alternative positionof the adjustable saddle seat;

Figure 8 is an elevation corresponding to Figure 7, showing anotheralternative position of the adjustable saddle seat;

Figure 9 is a diagrammatic elevation showing a possible method ofattaching the scaffold to a tree branch or other obliquely extendingfixed support;

Figure 10 is a fragmentary top plan view of the scaffold with the workplatform mounted thereon in place of the saddle seat;

Figure 11 is an end elevation of the work platform shown in Figure 10;

Figure 12 is a fragmentary side elevation of the scaffold and platformshown in Figure 10; I

Figure 13 is a detail view, partly in section, showing the scaffoldframe lock and cam release therefor; and

Figure 14 is adetail' view corresponding to Figure 13 showing the framelock in released position.

Having reference now to the drawings, wherein like reference numbersdesignate the same part in'all the views, Figures 1 and 2 show thescaffold or temporary support in operable position on a tree or poleindicated in dash lines. The main strength member of the scaffold frameis a strut 20, Figure 2, of some material such as aluminum, the strutbeing in the form of a reverse or S-curve. At the upper curve of thestrut a pair of tubular yoke members 21 is secured thereto as by apivotal connection 22. Members 21 extend forwardly from the strut andthe forward, spaced apart ends thereof pass with a sliding fit throughaligned bores in an openended, rectangular box structure 24 which servesto hold the yoke members in fixed relation to one another in the sameplane.

Secured to opposite sides of the strut 20 as by a pivotal connection 25is a pair of links 27 which extend forwardly and upwardly, the forwardends thereof being pivotally secured to a rod 28 which is mounted on thebox structure 24 by means of eye bolts 39, Figures 1, 2 and 5. Anactuating lever or rod 31 passes through aligned bores in the links 27with a free fit and a cam element 32, Figures 13 and 14, is fixed on thelever between the links. A narrow channel shaped member 34 is pivotallysecured to the strut 20 by means of the same connection 22 which securesthe yoke members thereto, the channel member bottom being cut away as at35 to permit the member to straddle the strut inside the yoke members.The channel member 34 extends forwardly and downwardly between the links27 and is formed with aligned slots 37 in its sidewalls which receivethe actuating lever 31 when the scaffold is in extended, operableposition as shown in Figures 1, 2 and 13.

A tension spring 38 extends between the forward end of the channelmember and a strap 40 on the strut 20, Figure 2, and this spring exertsa downward force on the member which normally holds the lever or rod 31in engagement with the slots 37. This locking arrangement prevents theyoke members 21 and strut 20 from swinging together and collapsing thescatfold frame but it can be released when desired by pulling upwardlyon the handle portion of the actuating lever. Upward movement of thelever causes the cam element 32, positioned between the sides of thechannel member, to rotate in a clockwise direction, Figures 13 and 14,and force the member upwardly so that the lever 31 becomes disengagedfrom the slots 37. This permits the yoke members and strut 20 to swingtogether, the links 27 causing the box structure 24 to slide forwardlyon the yoke members during such movement, so that the scaffold frameoccupies a smaller area and is more compact for carrying or storing.

Pivotally secured to the forward extremity of each yoke member 21 is agrab arm 41, Figure 1, which is preferably formed of steel and issubstantially arcuate in shape. The grab arms are provided with aplurality of sharp teeth 42 which are adapted to engage the tree, poleor' other upright support upon which the scaffold is mounted, the teethbeing angularly disposed at predetermined angles with respect to thearms in order to bite into the support in the most effective possiblemanner. One end of a link 44 is secured to each grab arm 41 by means ofa lost motion connection 45, and the other ends of these links arepivotally secured to the forward ends of L-shaped pull rods 47 which areslidably supported by the box structure 24. The pull rods extendrearwardly from the box and terminate in operating handles 48 withineasy reach of the workmans saddle seat 50, to be described in greaterdetail hereinafter. By pushing or pulling on the handles 48, the workmancan swing the grab arms into or out of engagement with trees and polesof various diameters as will be more fully explained presently.

Positioned between the forward extremities of the yoke members 21 are aplurality of spikes 51 which are adapted to engage the portion of theupright support that is directly adjacent the scaffold. In theembodiment of the invention illustrated, there are three such spikes,the center spike being slightly shorter than the two outer spikes sothat the points of the spikes lie on a curved line which conformsroughly with the curved surface of the support. Spikes 51 are slidablymounted in transversely aligned bores 52 in the side walls of the boxstructure 24, Figure 5, and are fixedly secured to a common bar 54positioned longitudinally within the box. The bar 54 is moved laterallyin the box structure, to move the spikes into or out of engagement withthe/upright sup.- port, by means of a pair of actuating arms 55, Figures1-4, which are swingably mounted on a rod 57 supported by brackets 58secured to the top wall of the box structure. The forward end portionsof the arms 55 extend through slots in the top wall and are formed witharcuately shaped cam openings 60 which engage with opposite end portionsof the bar so that swinging movement of the arms imparts lateralmovement to the bar and spikes, the spikes being projected intoengagement with the support when the arms are swung downwardly, orclockwise as viewed in Figures 3 and 4, and retracted out of engagementwhen the arms are swung upwardly. The rear sides of the arcuate camopenings 60 are formed with cam lobes or projections 61 which engage bar54 when the arms are being swung downwardly and impart an addedthrust tothe spikes entering the support. These cam lobes also help to maintainthe spikes in position when they are fully engaged as in dicated inFigure 3. p

The actuating arms 55 are operated in unison by means of an operatinghandle 62 which joins the rear ends of the arms and is located so thatit is within easy reach of a workman seated on the saddle seat 50. Inorder to positively lock the arms in down position when the spikes areengaged with the upright support, a ratchet and pawl structure isprovided comprising a ratchet wheel 64 and a pawl 65. Wheel 64 ismounted on rod 57 and is fixed to one of the arms so as to turntherewith. Pawl 65 is swingably mounted on rod 28 and is normally urgedinto engagement with the ratchet wheel by a coil spring 67 which is alsopositioned on rod 28 and has a hooked end extension engaging the pawl asat 68, Figures 3 and 4. The ratchet and pawl operate in the usual mannerwith the pawl tooth sliding on the teeth of the ratchet wheel duringdownward movement of the actuating arms but preventing upward movementof the arms until it is lifted out of engagement with the wheel by meansof the tab 70 formed on the pawl for that purpose.

Having reference now to Figures 2 and 6, the lower end of the mainstrength member or strut 20 has secured thereto as by a weldedinterlocking connection an elongated tube 71 of square cross-section,the tube being disposed in substantially perpendicular relation to thelongitudinal axis of the strut. The tube 71 serves as a footrest for theworkman seated on the saddle seat 50 and is provided with small endplates 71a to keep the workmans feet from sliding off the tube. AU-shaped rod 72 is passed through a transverse bore in the strut 20 andaligned bores in the side walls of the tube so that the ends 73 of therod extend outwardly from the front side of the tube as shown. The endsof the rod are threaded so that nuts 74 may be positioned thereon tosecure the rod in position, and the extremities thereof are sharplypointed making the rod ends into spikes which are adapted to engage theupright support at a point spaced below the grab arms 41 and slidablymounted spikes 51, as indicated in Figure 2. Since it may, in certaininstances, be more convenient for the workman to work in a standingposition, a platform 75 of suflicient size to enable a workman to standcomfortably thereon is provided adjacent the footrest tube 71. Platform75 is a supported at its rear end by means of a pair of links 76 securedto the strut 20 at the pivotal connection 25.

The forward end of the platform is supported by means of a bracket orangle iron 77 which is secured to the ends of the rod 72 as by the nuts74.

The workmans saddle seat 50 is adaptedto be positioned on the rear endportion 79 of the strut 20, this portion of the strut being insubstantially horizontal position when the scaffold is attached to avertical or upright support as shown in Figure 2. The seat is providedwith a pair of depending parallel plates 80 which are spaced apart topermit the end portion 79 of the strut to be received therebetween witha free sliding fit. The plates are formed with a plurality of alignedbores 81 which coact in various arrangements with a plurality of bolts82 to enable the seat to be adjustably positioned at different angles onthe strut. Thus, if the bolts are placed in the top pairs of bores,Figure 2, the end portion 79 of the strut will be positioned between thebolts and seat bottom so that the seat is mounted in a horizontalposition, or parallel to the end portion of the strut. If, on the otherhand, the bolts are arranged in the bores as shown in Figure 7, the endportion of the strut will be positioned between the bolts so that theseat has a forward tilt with respect thereto. Similarly, an arrangementas shown in Figure 8 will permit the seat to have a backward tilt withrespect to the end portion of the strut. In all of these arrangementsthe bolts-are removably secured in the bores by means of wing nuts (notshown), and the seat 50 is prevented from sliding off the rear end ofthe strut by means of a bolt and nut positioned in a bore 34 in the endof the bar. One reason for providing for angular adjustment of thesaddle seat is shown diagrammatically in Figure 9 wherein the scaffoldis attached to an obliquely extending tree limb and it is desirable tohave the seat in a substantially horizontal position even though thescaffold frame necessarily tilts downwardly.

The scaffold is adapted to be hoisted up into position 1 on the uprightsupport by means of a sling (not shown) which cooperates in the usualmaner with a block and tackle arrangement. The sling is preferablyattached to the scaffold at four points whose location has beenpredetermined so that the scaffold will be in balance during the hoist,remaining in substantially the same position as shown inFigure 2 at alltimes. The attachment points are at the rings 85 secured by brackets 87to the yoke members 21, Figure 1, and at the eyes 83 in the ends of anelongated rod 90 disposed at right angles to the bar 20. Rod 90 issupported by a U-shaped bracket 91 which is slidably mounted in invertedposition on the end portion 79 of the strut 20, Figure 2. The bracket isprovided with a nut and bolt ararngement 92 which is adapted to draw thesides of the bracket together and thus secure it in any adjustedposition on the strut. If desired, the bracket can be inverted from itsFigure 2 position and mounted on the end portion of the strut behind thesaddle seat 50 so that the rod 90 is positioned above the strut. Thismay be of advantage if the workman is seated on the scaffold during thehoisting since the ropes secured to the eyes 88 in the rod will thenpass on either side of his body giving him added support. A ring 94 ismounted on the rod 90 between the sides of the bracket 91 so that, afterthe scaffold has been attached in the desired position on the uprightsupport, a line may be passed therethrough to haul up tools, suppliesand the like.

In order to facilitate hoisting the scaffold up into position on theupright support, particularly when the workman is already seated thereonduring the hoisting, an auxiliary dolly 95, Figures 2 and 6, may beattached to the scaffold, the dolly having wheels which engage the sideof the support to reduce friction and space the spikes 51 and 73.outwardly therefrom. Dolly 95 is essentially comprised of a rectangularangle iron frame which is secured to the scaffold by positioning the.flange 97 on the top member 98 of the frame between double nuts on theeye bolts 30, Figure 3, and attaching the bottom member 101 of the frameto the footrest tube 71 as by bolts 102, the bottom member beingobliquely disposed with respect to the main plane of the frame in orderto fit in overlying relation with the tube as shown in Figure 2. Theside members 104 of the frame are obliquely disposed with respect to thetop and bottom members, Figure 6, so that the wheels 105 will squarelyengage the curved surface of the upright support. The yoke 107 whichrotatably supports each wheel is mounted on one leaf of a hinge member108, the other leaf being secured to the frame side member. The twohinge members 108 on each side member are provided with a singleelongated hinge pin 110 which extends upwardly from the frame andterminates in a handle 111 above the box structure 24, Figure 2. Thehinge pins are keyed to yoke supporting hinge leaves so that the handles111: can be turned to swing the wheels 105 out of engagement with theupright support as indicated on one side in Figure 6. A spring (notshown) engages the upper portion'of each hinge pin, however, andnormally holds it so that the hinge leaves are together with the wheelsin support engaging position. The two wheels 105 at the bottom of thedolly frame are preferably slightly larger than the two upper wheels toallow for the. taperof a tree or pole and also to space the bottom ofthe scaffold frame away from thesupport so that the bottom spikes 73will clear during hoisting. When the auxiliary dolly 95 is attached tothe scaffold, it will be understood. that the latter can not becollapsed as previously described even though the locking arrangement isdisengaged by the actuating lever 31.

In operation, a sling is attached to, the scaffold as previouslyexplained, and the. scaffold is hoisted up to the desired work positionon the upright support. With a proper block and tackle arrangement. theworkman can sit onthe, scaffold and pull himself up, or others on theground can pull him up. In the alternative, the workman can stay on theground and hoist the scaffold into position and then climb up himselfusing his spurs in the usual manner. In any case, once the scaffold isin position and while the sling is still attached, the handles 111 areturned to swing the' wheels 105 out of engagement with the support. Thebottom spikes '73 will then engage the support and if the workman isalready seated on the scaffold they will penetrate deeply due to hisweight. The grab arms 41, which are usually wide open during thehoisting as shownin dash lines in Figure 1, are then swung intoengagement with the support by means of the operating handles 48.Thereafter, the slidable spikes 51,. which are in retracted positionduring the hoisting, are forced into engagement with the support byswinging'theactuating arms 55 downwardly with the operating handle 62.The scafiold is then securely attached to the support with the bottomspikes 73in effect serving the same purpose as the workmans boot spursand the grab arms 41 serving the same purpose as his waist harness inthe old, uncomfortable supporting arrangement. The slidable spikes 51provide added security and' stability sinceth ey not only firmly engagethe upright support but positively prevent any slipping or twisting ofthe scaffold as well. With this arrangement, the weight of the workmanand any additional weight supported by the scaffold only causes theteeth 4-2 on the grab arms and the bottom spikes 73 to penetrate theupright support more deeply.

The scaifoldis adapted for use with upright supports of varyingdiameters since the grab arms 41 can be used in their wide open positionas shown in dash lines in Figure 1 and engage a support having adiameter as large as 30 or the arms may be overlapped to engage asupport having a considerably smaller diameter. the arms are used intheir open position, it is usually desirable to supplement them with achain which can be passed around the support and have its ends fastenedto hooks 112 on the ends of the arms, Figure 1, or two chains can beused, each extending between the hook on one of the grab arms and a snapconnection 114 on the opposite side of the scaffold frame as shown inFigure 1. The chain or chains can, of course, be used in many other waysand can, if desired, even be used when the grab arms 41 are used inoverlapping relation on a relatively small support.

. Figures -12 show a platform 115 which may be secured to the scaffoldframe in place of the saddle seat 50 and which will support as many asthree standing men at one time. The platform is fastened at its rear endto the end portion '79 of the strut 20 by means of depending parallelplates 117 which are spaced apart to receive the end portiontherebetween, the plates having aligned bores so that a bolt 118 can bepassed therethrough to draw the plates into tight engagement with theend portion. The front end of the platform 115 is fastened to the yokemembers 21 by means of U-bolts 120 which pass around the members andextend up through holes in the platform so that nuts 121 can be securedto the ends thereof to hold the parts together. An angular bar 122 ismounted on each end of the platform, the bars providing substantiallytriangular end supports as shown. A rope or line 124 may be stretchedbetween the bars 122 to provide a knee grip or support for a standingworkman if desired. Since the platform is necessarily positioned overthe actuating arms 55 and operating handle 62 for the slidable spikes51, a hinged panel 125 is provided in the platform to permit operationof these parts when the platform is mounted on the scaffold.

While the invention has been particularly described with relation to awork support for workmen such as tree surgeons and telephone or powercompany linemen, it will be apparent that the scaffold herein describedcan be used for many other purposes. For example, the spikes and teethcan be provided with friction-gripping hard rubber covers so that thescatfold can be used on metal upright supports such as fiagpoles, mastsand the like. The scaffold with platform and a protective cover couldalso be used in a tree as a deer hunters watch post or military sniperspost. Two or more scaffolds can be attached to an upright support atsubstantially the same level so that planks can be secured thereto toprovide a larger work station for a number of workmen. Otherapplications will undoubtedly occur to those skilled in the art, and allsuch applications are intended to be included within the scope of theinvention.

This invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The embodimentdisclosed is therefor to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims.

What I claim is:

1. A device of the character described comprising a frame, a pair ofgrab arms pivotally secured to said frame, mechanical means to move saidarms into or out of engagement with an upright support, a plurality ofspikes slidably mounted on said frame, mechanical means to move saidspikes into or out of engagement with the upright support, and aplurality of spikes fixedly secured to said frame and engageable withthe support at a point below said arms and slidably mounted spikes.

2. A device of the character described comprising a frame, means tosupport a workman on the frame, a pair of arcuate grab arms pivotallysecured to said frame and swingable into and out of engagement with anupright support, mechanical means operable from points adjacent saidworkmans support to actuate the swinging movement of said arms, aplurality of spikes mounted on said frame for slidable movement into andout of engagement with the upright support, mechanical means operablefrom a point adjacent said workmans support to actuate the slidingmovement of said spikes, and a plurality of fixed spikes secured to saidframe and engageable with the upright support at a point below said armsand slidably mounted spikes.

3. A device of the character described comprising a collapsible frame,locking means to maintain said frame in extended operable condition,means detachably se cured to said frame to support a workman, a pair ofarcuate grab arms pivotally secured to said frame, said arms beingswingable into and out of engagement with an upright support in a planenormal to the axis of the support, mechanical linkage operable frompoints adjacent said workmans support toactuate the swinging movement ofsaid arms, a plurality of spikes mounted on said frame in substantiallythe same plane as said grab arms, said spikes being slidably movableinto and out of engagement with the upright support in a plane normal tothe axis of the support, means operable from a point adjacent saidworkmans support to actuate the sliding movement of said spikes, footrests secured to said frame at a point spaced below the plane of saidarms and slid ably mounted spikes, and a fixed spike secured to saidfoot rests and engageable with the upright support at an angle obliqueto the axis of the support.

4. A device as defined in claim 3 wherein said workmans support is asaddle seat.

5. A device as defined in claim 3 wherein said workmans support is asubstantially flat platform.

6. A device as defined in claim 3 together with guide roller means onsaid frame adapted to engage the upright support while the frame isbeing hoisted up into position on the support.

7. A device of the character described comprising a frame, means tosupport a workman on the frame, a pair of arcuate grab arms pivotallysecured to said frame and swingable into and out of engagement with anupright support, actuating means for said arms positioned adjacent saidworkmans support, means operably connecting said arms to said actuatingmeans, a plurality of spikes mounted on said frame for slidable movementinto and out of engagement with the upright support, a cam actuatorpositioned adjacent said workmans sup port and operable to effect thesliding movement of said spikes, means to lock said cam actuator in anyone of a number of predetermined operating positions, and a plurality offixed spikes secured to said frame and engageable with the uprightsupport at a point below said arms and slidably mounted spikes.

8. A device as defined in claim 7 together with means on said grab armsto attach an auxiliary chain thereto.

9. A device as defined in claim 7 together with means on said frame toattach an auxiliary chain thereto.

10. A device of the character described comprising a collapsible frame,releasable locking means to hold said frame in extended operablecondition, means detachably secured to said frame to support a workman,a pair of arcuate grab arms pivotally secured to said frame, said armsbeing swingable into and out of engagement with an upright support in aplane normal to the axis of the support, actuating means for said armspositioned adjacent said workmans support, means operably connectingsaid arms to said actuating means, a plurality of spikes mounted on saidframe in substantially the same plane as said grab arms, said spikesbeing slidably movable into and out of engagement with the uprightsupport in a plane normal to the axis of the support, a cam actuatorpositioned adjacent said workmans support operable to effect the slidingmovement of said spikes, means to lock said cam actuator in any one of anumber of predetermined operating positions, foot rests secured to saidframe at a point spaced below the plane of said arms and slidablymounted spikes, and a plurality of fixed spikes secured to said footrests and engageable with the upright support at an angle oblique to theaxis of the support.

11. A device as defined in claim 10 wherein said workmans support is anangularly adjustable saddle seat.

9 10 12. A device as defined in claim 10 wherein said workon said grabarms and frame to attach an auxiliary chain mans support is asubstantially fiat platform. thereto.

13. A device as defined in claim 10 together with guide 15. A device asdefined in claim 10 wherein each of roller means on said frame adaptedto engage the upright said grab arms includes a plurality of angularlydisposed support While the frame is being hoisted up into position 5teeth. on the support.

14. A device as defined in claim 10 together with means No referencescited

